i have a craftsman mower with a 18 hp b&s motor it starts and runs good but if you shut it off hot and try to?

This is typical of a failing ignition coil. When you shut the engine off the Temperature goes up due to loss of cooling air to the engine. The coil will fail until it cools and than work normally again. Next time you shut it off and it won't start, check the spark. If there is none consider replacing the coil.

Your problem is either with the ignition coil over heating or with the spark plug. Take the plug out first and change it for a new one. You see what is happening is the insulator is clogged with debris and this is hard to get off without breaking the insulation. When the engine gets real hot, the spark is tracking along the carbon on the plug, so instead of the spark going to the gap, the current is crossing the carbon to the ground. If it's the ignition coil, you need to replace it.

Try it and report back.

XX

If you mean the starter spins but the engine does not turn over when hot , then I would suspect a starter issue. Try tapping it when you are cranking it over and see if it engages.

it looks like you tempometer is all ****** up! you should get it fixed RIGHT AWAY